Abstract
Changes in chromosome number impair fitness by disrupting the balance of gene expression. Here we analyze mechanisms to compensate for changes in gene dose that accompanied the evolution of sex chromosomes from autosomes. Using single-copy transgenes integrated throughout the Caenorhabditis elegans genome, we show that expression of all X-linked transgenes is balanced between XX hermaphrodites and XO males. However, proximity of a dosage compensation complex (DCC) binding site (rex site) is neither necessary to repress X-linked transgenes nor sufficient to repress transgenes on autosomes. Thus, X is broadly permissive for dosage compensation, and the DCC acts via a chromosome-wide mechanism to balance transcription between sexes. In contrast, no analogous X-chromosome-wide mechanism balances transcription between X and autosomes: expression of compensated hermaphrodite X-linked transgenes is half that of autosomal transgenes. Furthermore, our results argue against an X-chromosome dosage compensation model contingent upon rex-directed positioning of X relative to the nuclear periphery.
Article and author information
Author details
Funding
National Institutes of Health (1R01 GM030702)
- Barbara J Meyer
Howard Hughes Medical Institute
- Barbara J Meyer
National Institutes of Health (1F32 GM100647)
- Bayly S Wheeler
Howard Hughes Medical Institute
- Christian Frøkjær-Jensen
National Institutes of Health (1R01 GM095817)
- Erik Jorgensen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Edith Heard, Institut Curie, France
Publication history
- Received: April 29, 2016
- Accepted: August 29, 2016
- Accepted Manuscript published: August 30, 2016 (version 1)
- Accepted Manuscript updated: September 1, 2016 (version 2)
- Version of Record published: October 3, 2016 (version 3)
Copyright
© 2016, Wheeler et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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